1. Field of the Invention
The present invention relates to an illumination device that illuminates an inner peripheral surface of a tire, and an inspection device of a tire.
2. Background Art
Normally, a tubeless tire is vulcanized and becomes a finished tire by stacking members such as an inner liner, a carcass, a belt, and a tread on a molding drum to mold a non-vulcanized tire, charging the same in a mold, performing an extended deformation by shaping using a bladder, and heating the same while pressing against a mold surface. In order to improve mold releasability from the bladder after vulcanizing, a water-soluble releasing agent or the like is applied to an inner liner of an inner surface of the non-vulcanized tire.
In the manufactured tire, linear concave and convex portions extending in a tire width direction may appear on an inner peripheral surface of the tire due to irregularity of members and the like during manufacturing. Specifically, when both end portions of a carcass ply, in which a steel cord or a high strength organic fiber cord is arranged in the tire width direction, are not overlapped with each other but a gap is formed therebetween, a linear concave portion is generated. Furthermore, when the overlap of a joint portion of the carcass ply is greater than a predetermined amount, a linear convex portion is generated. Furthermore, even when the steel cord of the carcass ply is penetrated through the inner liner and is protruded to the inner surface side of the tire, a linear convex portion is generated.
In such a tire, in which linear concave and convex portions exist on the inner peripheral surface, there is a strong concern that the stability of the tire is low. Thus, the existence of concave and convex portions exceeding a predetermined standard value is examined before shipping the tire (for example, see JP-A-2002-286645).
In JP-A-2002-286645, as an illumination device that is used when inspecting the inner peripheral surface of the tire, a device is disclosed which images an inspection region of the inner peripheral surface of the tire illuminated by the lighting of a light emitting portion provided in a light source unit by a CCD, makes a density distribution of light of the inspection region based on the imaged result, calculates a difference between light intensities targeted for each image angle taken by each light source unit in the density distribution, and controls the light emission amount of the light emitting portion.
However, in the illumination device such as JP-A-2002-286645, there is a problem in that, in order to make the light intensity reflected from the inspection region of the inner peripheral surface of the tire uniform, shadows are not cast even when the linear concave and convex portions exist on the inner peripheral surface of the tire, and it is extremely difficult to detect an existence of the concave and convex portions.
Furthermore, when applying the releasing agent to the inner surface of the non-vulcanized tire, the releasing agent floods the joint portion of the inner liner, and a bulge having a height of about 0.2 to 1.0 mm called air stagnation is generated on the inner peripheral surface of the tire.
When the air stagnation exists on the inner peripheral surface of the tire, since there is a fear that an air leakage of the tubeless tire occurs or the durability may decline, the existence of the air stagnation is inspected before shipping the tire (for example, see JP-A-2001-249012 described as below).
JP-A-2001-249012 discloses an inspection device of a tire in which the photographing means photographs light from the inner peripheral surface of the tire reflected by a mirror while relatively rotating a tire and the photographing means around an axis of the tire in the state of illuminating the inner peripheral surface of the tire by the illumination means.
In the inspection device of the tire disclosed in JP-A-2001-249012, the mirror which reflects the light from the inner peripheral surface of the tire to the photographing means is inserted in a recessed portion that is recessed radially outward from a hollow portion of the tire. In such a case, in order to increase a region that can be photographed in a circumferential direction of the tire, since the inner peripheral surface of the tire forms a circular arc shape, the mirror is deeply inserted from the hollow portion into the recessed portion, whereby it is difficult to make the tip portion of the mirror approach the inner peripheral surface of the tire. For that reason, there is a problem in that, in order to increase a region that can be photographed by the photographing means in the circumferential direction of the tire per unit time to reduce the time necessary for the inspection of the whole periphery of the tire, the range of the inner peripheral surface of the tire, which can be imaged by the photographing means, is narrowed, whereby the inner peripheral surface of the tire cannot be inspected over a wide area.